Self-organisation through nonequilibrium catalytic activityÂ
Particles that are both catalytically-active and chemotactic can interact through the chemical concentration fields upon which they act. Examples of such particles include micron-scale chemotactic microorganisms and phoretic colloids, as well as nano-scale enzymes. I will discuss the range of spatio-temporal self-organization phenomena that can emerge in mixtures of catalytic particles. Due to their nonequilibrium origin, the effective interactions among catalytic particles can display exotic features such as nonreciprocity (e.g. A is attracted to B while B is repelled from A), which results in dynamic steady states with self-propulsion [1], periodic oscillations [2], or aggregation in spite of self-repulsion [3]. Importantly, the complexity of the metabolic network in which such catalytic particles participate translates into a rich structure in the network of effective interactions that emerges among them, and has a strong effect in the resulting self-organization [4]. Lastly, I will discuss how, far from being an ad-hoc effect, the emergence of effective interactions among catalysts is an unavoidable consequence in any thermodynamically-consistent theory of a catalytically-active mixture [5].
[1] J. Agudo-Canalejo and R. Golestanian, Phys. Rev. Lett. 123, 018101 (2019)
[2] V. Ouazan-Reboul, J. Agudo-Canalejo, and R. Golestanian, Nat. Commun. 14, 4496 (2023)
[3] V. Ouazan-Reboul, R. Golestanian, and J. Agudo-Canalejo, Phys. Rev. Lett. 131, 128301 (2023)
[4] V. Ouazan-Reboul, R. Golestanian, and J. Agudo-Canalejo, arXiv:2510.21430 (2025).
[5] M. W. Cotton, R. Golestanian, and J. Agudo-Canalejo, Phys. Rev. Lett. 129, 158101 (2022)